The present disclosure is generally directed to the fields of communications, software and navigation, including, for example, to methods, architectures, apparatuses, systems directed to dead reckoning for pedestrian navigation (“pedestrian dead reckoning”) and robust heading estimation in pedestrian dead reckoning.
Pedestrian dead reckoning (PDR) has uses in a variety of environments, applications and services. For instance, emergency personnel may be able to locate a person in an indoor environment under adverse conditions using mobile devices/applications employing PDR (e.g., in connection with location-based services). Other examples include customer navigation in shopping malls, supermarkets, etc.; traveler navigation in airports or train/subway stations and the like. PDR can be used to augment GPS and other location technologies (e.g., improve the tracking between satellite updates, help resolve positional errors caused by multi-path reception, fill in times where there is no signal, etc.), as well.
PDR, in general, involves advancing a previously determined position associated with the pedestrian using with a distance and direction that the pedestrian walks, e.g., on a step-by-step basis. Conventional PDR relies on revising the previously determined position using only a length of a current step and a heading of either the start or the end of the current step (where the current step is the first step after such position is determined). Such conventional PDR is prone to errors due to inconsistent and/or inaccurate step detection, inconsistent and/or inaccurate stride length computation and/or inconsistent and/or inaccurate walking direction computation. Missed or false steps, walking direction drift and mis-estimated stride length, for example, affect PDR accuracy. Further, assuming a magnetometer is employed, environment magnetic field interference can exacerbate walking heading error(s). Once introduced, the errors are carried forward each step taken thereafter. The carrying forward of the errors exacerbates PDR inaccuracy due to each determined position that follows the introduced errors including the prior determined position inaccuracy. And unless controlled, the carrying forward of the errors, especially those associated with heading and/or that distort walking trajectory, may make any resulting conventional PDR determination unsuitable for integration with mapping or other positioning signals, e.g., GPS or GPS-like indoor positioning measurements, and in turn, for use in various environments, such as indoors.